Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753696Ab2HTTNy (ORCPT ); Mon, 20 Aug 2012 15:13:54 -0400 Received: from usindpps03.hds.com ([207.126.252.16]:57720 "EHLO usindpps03.hds.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753250Ab2HTTNv convert rfc822-to-8bit (ORCPT ); Mon, 20 Aug 2012 15:13:51 -0400 From: Seiji Aguchi To: "linux-kernel@vger.kernel.org" , "Luck, Tony (tony.luck@intel.com)" , "Matthew Garrett (mjg@redhat.com)" , "dzickus@redhat.com" , Mike Waychison CC: "dle-develop@lists.sourceforge.net" , Satoru Moriya Subject: [RFC][PATCH v2 0/3] make efivars/efi_pstore interrupt-safe Thread-Topic: [RFC][PATCH v2 0/3] make efivars/efi_pstore interrupt-safe Thread-Index: Ac1/BzifQj+EBOmdQMa+fIK8DRfpaA== Date: Mon, 20 Aug 2012 19:13:36 +0000 Message-ID: Accept-Language: ja-JP, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.74.43.113] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.7.7855,1.0.260,0.0.0000 definitions=2012-08-20_04:2012-08-20,2012-08-20,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_policy_notspam policy=outbound_policy score=0 spamscore=0 ipscore=0 suspectscore=1 phishscore=0 bulkscore=60 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=6.0.2-1203120001 definitions=main-1208200220 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2093 Lines: 45 Changelog - Patch 1/3 Add spin_lock_irq/spin_unlock_irq to open/close callbacks of efi_pstore instead of moving spin_locks to a read callback. - Patch 2/3 Replace a periodical timer with schedule_work(). - Patch 3/3 freshly create to kick a workqueue in oops case only. [Problem] There are following problems related to an interrupt context in efivar/efi_pstore. Currently, efivars enables interrupt while taking efivars->lock. So, there is a risk to be deadlocking in a write callback of efi_pstore if kernel panics in interrupt context while taking efi_lock. Also, efi_pstore creates sysfs entries ,which enable users to access to NVRAM, in a write callback. If a kernel panic happens in interrupt contexts, pstore may fail because it could sleep due to dynamic memory allocations during creating sysfs entries. To resolve the problems above, a goal of this patchset is making efivars/efi_pstore interrupt-safe. [Patch Description] Patch 1/3 efivars: Disable external interrupt while holding efivars->lock This patch replaces spin_lock/spin_unlock with spin_lock_irqsave/spin_lock_irqrestore to make efivars interrupt safe Patch 2/3 efi_pstore: Introducing workqueue updating sysfs entries This patch removes sysfs operations from write callback by introducing a workqueue updating sysfs entries Patch 3/3 efi_pstore: Skip scheduling a workqueue in cases other than oops This patch restricts a schedule of a workqueue in just oops case which is truly needed for users. Also, a logic of erase callback is freshly created instead of sharing with a write callback so that its sysfs update operation works correctly. drivers/firmware/efivars.c | 209 +++++++++++++++++++++++++++++++++++++------- include/linux/efi.h | 3 +- 2 files changed, 179 insertions(+), 33 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/